I need to fix an issue with my friends mac, but I do not know his pass, and don't want to have to make up a new one, can I disable it in recovery mode or single user mode, then re-enable it after I've sorted the issue and logged into his account, and have his default pass' restored?
You can reset the password via Recovery Mode or Single User Mode, but you would need to know the original password in order to change it back.
Another important issues comes to mind if they're using FileVault. You will not be able to access their information by changing their password (and you'll likely break other things trying).
Other options would include:
- Making a secondary account (if the issue isn't specific to that user account)
- Repairing the issue via Target Disk Mode (if the issue is fixable that way, and they aren't using FileVault)
- Obtaining the password, or having them change it to a temporary password they can share with you
Note: If they aren't running FileVault, and you end up changing their password, you'll be prompted to wipe out their Keychain on every boot (which means they lose everything, or you continuously see Keychain errors).
The third option, i.e. obtaining a correct password, is best, and standard practice for repair shops.
If you change a users password via the recovery partition it stays on the new password until you change it again. To change it to the old value you need to know the old password.
The only thing not affected is the keychain password, you need to enter the old password to get access to the keychain.